Telephone system



R. s. WsLBUR.

TELEPHONE SYSTEM.

lAPFUCATION FILED DEC. 27,1918.

Patented July 5, 1921.

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'NES TEEN TTIETBLC TELEFHQUE 5 S4 ill/Eileen, :1 cii- To @ZZ wfz am. We@ come be it known dial l, ik

aen wies? residing et Lyndhurst, eouuy ei' Bergeng of New 7-rsq/ :mvo ted cetam new am?. usean U t v` currents oubiie ef ne range e1; ei inni telephone 0r voice Currents ever :i tr sien line fer the i rpoe 'libia india en ige an e for reinfeieinm' el' repeainr veive enrrens, und also te provide Geri; A1 eonilinntiens of i renting a# fili 0i this med for enunion of lie .eiee Cin-renie, zipper ne le ordinarily de.,

VR m18 eiiicieni: xmnsniissien of cui-renfe of voice er eleplifme it is desirable und L, to transmit over the sume irenenn line, currents web lower er beinveen Sulxccrilier g 'for exuinp-iejsifl ing; wur 'en usually i irei'gneney adapted le ncuufe n bell, which blyiuiipg current is umnlnenljf lin-Jun in 'liieur AS ringing cuiA rFliese ringing vnrren'rs :ire n/ienu- :den e e fraaie? degree than the Toi/:e nu r i sini-Q Elie ransniission line is not dej'nml tu trzmsniii currents 0f illie ringing iranienne* :it lie liigjlies eliiciejuvy, lms therefore been Gemmell io pre Tide, usually ai' :i repeater Station, :in eleeromzignel'ir de- Vif-e which would respond i0 ringir j euri-ent fleniing in over one end of the lineIl which. in respeinling, would connect :meileur Sourre 'ii rinf reni. i0 ille line en ile other ier, illus^ in @lievi repeeing ils u eertuin definite reugtli of :ringing` eurren is nii-essay Operate e ringing current Speiislive deviate, the range over which sncli. device could lie opezii'ed deie .ined by the impedance Qi' 'tiie line between "he point where die ringing Current is inmieseed on lie line amd tile location el" th i 1fesponei've device, and also by the impedanee of Cerwin appamus ordinii-lily assoeia'led fiers Eatenz.

Oee Currents. Thus, lie usual been bric iinwing across ammini-seien l1 e,

ne neighboriieed @if the regmiug H- x acress die il' peintfo the output coii @f such i'epe Velien Such connection is r1 lia the bridged input ce ferme parallel circuiti el* rinning responG-e relay. Und@v -i ns glie i" I range Could n e r @sed beyond ce iD r erniined neig lie line im ze e ringii'if Spensl ieiny but also i..M une@ iie shunt Circuit is an elojee of the present iii'ifeniei to increase the ringing of a transmission line which includes repeaing apparatus, and. in :1L-Comience with :i feature of 'lie invention this object attained ey inserting in 'ille riuismission line, beyond die point of Connection o?? the ringing' response device or relay, an impedance which ,is high cur- 4reiii of ringing frequency and which is inw io Currents of te. king frequency,- which impedance so decreases the sliugit effect lle input coil of the repeater or amplifying .device as to render such sliuiiiing eiiewm aim-0st negligible 'Echi' curreneoi" ringing frequency. The im'ent"n xivill, lie best understood from "lie Speel., tion and annexed drawing, in whirxh, the gure is diagramma'ie representation of :i portion of the transmission' line including the apparatus at a repeater station included in auch line.

in the drawing, if und L2 and L3 and L repri seni apposite ends oiv a telephone Luxus mission .line nding beiufeen wo widely sepureied peints. -ssociaded with such trenrmission line is a pair ei amplifying devices 1 and The amplifying device l 1S errang-ed to :unplify currents, impressed upon the conductors L1 und L2 und to iinsmh un'iplified currents on the. ce

L3. and L4. Simiiarly the amplifying' device 2 is arranged to anipii'fy currents impressed un ille cendneters; L3 und L, and ivo impr such ampliied euriens on the. These ampliieis are eendueio-s L and L2. of tli'eueildneu'n discharge tube ype, including; @ne headed lilamene 3 :ind al, the pleee electrodes 5 and 6 and `che euxilizlry ing the gain of the repeater.

connected through adjustable contacts to the' potentiometer 13,I which is used for adjust- Similarly the input circuit of the amplifier 2 includes a source of potential ilament 4, ,the auxiliary electrode output coil. coil is connected through movable cenitacts with the potentiometer 16. The outputcircuit of the amplifier 1 may be traced from a source of potential 17, through retardation l coil 18, and thence over parallel branches one extending through the plate electrode 5, filament 3, back to battery 17, the other throughthe output coil 19' baleto the other side of the battery. Similarly the output circuit of the ampliiier 2 includes the source of potential 17' and retardation coil 1.8', and two parallel branches, one` including the plate electrode 6, and filament' 4; and the other including the output coil 20.

Voice' currents impressed upon the line Lli---LL normally pass through the armature and normal contacts of the relay 21 through condensers 22, windings 23 and 24 of the output coil of the amplifier 2, and from midvpoint of the windings 23 and 24 through a filter comprising inductances 26 andbridge condensers 27 through the potentiometer 13 and the input coil 1210i the amplifier 1. It will be noted that the conductor L2 includes a normally `closed Contact of the relay' 28. The amplified currents pass through the winding 19 of the output coil and are therefore induced in the windings 29 of the output coil of the amplifier 1, from whence they `pass through condensers 30 and armatures and normal contacts of the relay 31 tothe line LiL-L4.

Voice currents impressed uponI thegline Lil-Ll1 pass through the armature and normal contacts of the relay 31 through condensers 3() and through the windings 29 of the output coil of the amplifier 1, and from the mid-point of suoli windings through the filter, rcomprising inductances 32 and bridge capacity 33, through the potentiometer 1G l tothe input coil 1.5 of the amplifier 2. The

` the relay 21 to ,'65

conductor LA1 includes a normal contact of the relay 28. The currents amplified by the amplifier 2 pass through the output coil 2() and are induced in the output coils 23 and 24 and pass from thence through the condensers 22, normal contact andarmature of the line Ll-LFC The filters referred to are for tlie purpose of filtering 44 frangeinent shown 8 and a winding'l'll of the` The winding 15 of the output out currents outside the range generally encountered in Voice currents and fiorpreventing the passage of currents of such fie.

quencies through theampliiers. Potentiometers 13 and 16 are adjusted to give the maximum gain for currents of voice' frequency. Connected across the windings 23 and 24 of the output coil of amplifier 2 is the artificial line 25, the purpose of which is to v-balance the line section Ll-Lz. Similarly the artificial line 26 is connected across the output coil 29 for the purpose of balancing line section lig-L, The entire circuit arand thus far described is designed' primarily for the eilicient transmission and amplification of currents of voice frequency. A

For signaling purposes, however, current having a frequency much below that of the voice frequency, -preferably approximating 1621;- cycles, is ordinarily used. There is provided at the repeater station bridged across the conductors L1-and L2 a relay 35 which is tuned to respond to current of ringing frequency, that is aboutl cycles, and to present a. high impedance to currents of voice frequency. A- similarly tuned relay 36 is connected across the conductors L3 and L".

Ringing current impressed upon the line L1-L- at the distant end of the transmission lineencounters at the `repeater station two parallel circuits, one of which'is directly across the conductors L1 and L2 and includes the relay 35; the other includes the condensers 22, windings 23 of the output coil of the amplifier 2, condensiei's 37, the arti.- ficial line 25 or a parallel branch of said last mentioned parallel circuit, which may be traced from'the mid-points of the wind- 'ings 23-24, through the liitering arrangeinr1 lay 28. lt will be observed that the relay 35 is connected directly across the line andV that there is included 'in the .shunt circuits Just traced thle condensers'l 22, in addition to various other inductances and capacity.

It is possible to select for the condensers f 22 condensei's which are designed to present little or no impedance to currents oi' voice frequency, but which, together with the-inductance in the shunt circuits just traced, present a .very high impedance tocurrents of ringing frequency. Therefore, practically all of the ringing current is divert/ed through ringing response relay 35.

As there is a certain definite minimum ot current upon which ringing response relays,

such as 35, may he made to operate satisfactorily, it is obviousv that by diverting practically all the ringing current transmitti l overthe line through it, that the range or length of transmission line over which such 4 A ringing response relay can beoperated is .greater than would bathe case if no precautions were taken to preventthe shunting of such relay by. other apparatus bridged acrossl the transmission` line.

The relay 35 in operating opens a circuit of the `normally energized relay 38, which in releasing its armature closes a circuit from battery 39 through the right-handwinding of the relay 28, contact and armature of the relay 38 to ground, and from battery through thel relay 3l, contact and armature of the relay 38 to ground. The relay 28 in operating establishes short circuits about the input coil l2 of amplifier l and the input coil l5 of amplifier 2, and thus prevents the pas,- sage of the ringing current through Such ampliers. The operation of the relay 3l connects a source of ringing current indicated by the plus an ductors L5 and L4; This source of ringing current may be of the saine frequency as that impressed upon the line Ll-LZ, or it may be of some other frequency. y

It will be obvious that ringing currents impressed upon line I--L will cause the operation of the relay 36 identically as in the case of relay 35, and the consequent de energization of the normally energized relay el() will cause the operation of the relays 28 and 2l. Relay 2l will connect a source of ringing current to the, line conductors L1 and L2.

What-is claimed is: y

li In combination With a telephone transmission line, a repeater, a conductive bridge connected across said lline for associatingl said repeater therewith, an electromagnetic responsive device responsive to currents havn ing a frequency outside of the .voice range bridged across said transmission line, and impedance means included in said repeater bridge presenting high impedance to currents outside the voice range.

2. In combination with a telephone transmission line, a repeater, an input circuit for said repeater bridged across said line, an electromagnetic ringing current responsive `device'also bridged across said line and tuned to respond to currents of ringing frequency, and impedance means included in said repeater bridge presenting high impedance to currents of ringing frequency.

3. In combination with a telephone transmission line, a telephone repeater, an input d minus signs to the concircuit for said repeater bridged across said tele hone line, a ringing current relay bri ged across said transmission line tuned to respond to currents of ringing frequency, and impedance means included between the point of connection of the ringing relay ridge and the input circuit of the repeater to render the repeater bridge of high impedance to currents of ringing frequency.

4. ln combination with a telephone transmission line, of a. plurality of repeaters associated therewith, an input coil of one of said repeaters bridged across said transmission line, an output coil of the other of said repeaters included in series With said transmission line, a ringi g responsive relay bridged across said transmission line, and impedance means for preventing the shuntfing of `ringing current from said relay bridge through the bridge formed by the said output and input coils. 4'

5. ln combination with telephone trans` mission line, a plurality of repeaters includegl in said line oneof said repeaters having an input coil connected in bridge across said'line and another having an output coil connected in series With said line, a ringing responsive relay connected in bridge Kcross said line intermediate one'endvthereof and said output coil, and means controlled by said ringing responsive relay to connect a source of ringing cnrrent to said line between said input coil and the other end of said line. y

6. In combination with a telephone transmission line, a pair of repeaters associated therewith, an input coil for each of said repeaters connected across said transmission line, an output coil for each of said repeaters connected in series with said transmission line, a pair of ringing responsive relays, each of said relays connected across said transmission line betweenv an end thereof and said output coil of the adjacent one of said repeaters, and meansl controlled .by each of said ringing responsive relays for connecting a source of ringing, current 'to said line between the oppositrJ end thereof and the adjacent one of said repeaters.

In Witness whereof, I hereunto subscribe my naine-this 20th day of December, A. D.

i918. RAY S. WLBR. 

